keep one's ear to the ground 全神贯注地听

【讲解】

to the ground有“全部，完全，彻底”之意。让耳朵完全瞀觉起来，引申为“全神贯注地听”。

【对话】

A:John! John!

A:约翰！约翰！

B:Er... Yes, Madam?

B:哦……老师。

A:What are you thinking about? You are distracting again. Keep your ear to the ground.

A;你在想什么？你又走神了！注意听讲。

B:I am sorry, Madam.

B:对不起，老师。